The most common and most likely answer to this crossword clue is the 7 letter word GENOMES
I've seen this crossword clue in The Daily Telegraph
G
E
N
O
M
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S
More clues leading to the result GENOMES
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The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does GENOMES mean?
GENOMES noun- The complete genetic information (either DNA or, in some viruses, RNA) of an organism.